This invention relates to a system for monitoring tire pressure in wheeled vehicles. More specifically, the invention is directed to a remote tire pressure monitoring system that monitors the tire pressure for each tire and indicates to the vehicle operator the unique location of each tire being monitored.
It is known to equip vehicle tires with mechanisms to indicate tire pressure. For example, it is known to include tire pressure sensors that communicate the tire pressure information to a vehicle operator via tuned circuits and radio transmitters. The tire pressure sensors are mounted within the tire air valve stem and transmit pressure readings at predetermined time intervals using radio frequency, directly to a centralized tire pressure monitoring receiver. However, such known tire pressure monitoring systems lack a mechanism for reporting pressure information for specific vehicle tires. Accordingly, when the tire pressure sensors communicate that tire pressure is low, the vehicle operator has to manually determine which specific vehicle tire or tires have low pressure (for example, the right front tire or the spare tire, etc.).
To aid in specific vehicle tire location identification, other tire pressure monitoring systems have been employed that include coding each of the tires with unique digital values to provide an identification code. However, there are drawbacks associated with coding the tires. One such drawback includes the need to re-code each of the tires when routine maintenance activities are employed, such as tire rotation or replacement. Because tire rotation places the vehicle tires in random locations, the service person in charge of rotating the tires must re-code to insure correct identification of the tires.
Another known tire pressure monitoring system includes using remotely located antennae that have a limited reception capability. The antennae are connected by coaxial cables to a centralized tire pressure monitoring receiver, and thus, the location of a particular tire pressure signal may be determined. However, use of coaxial cable is expensive, as it requires an excessive length to enable the cable to be strung throughout the vehicle to the various antennae.
Thus, there is a need for an improved tire pressure monitoring system that identifies the specific locations of the vehicle tires without requiring re-coding or the use of extensive coaxial cable to transmit data.
The present invention is directed to a tire pressure monitoring and identification system. The system includes a plurality of tire pressure monitors that transmit tire pressure information to a plurality of corresponding transponders. The transponders each have a unique identification code and transmits both the tire pressure data received from the tire pressure monitors and the identification code of the transponders to a central system receiver. The central system receiver provides the tire pressure data and location identification for each tire to a vehicle operator.
In accordance with one aspect of the invention, for every tire, at least one transponder is secured to the vehicle body proximate to the tire from which it is to receive tire pressure readings. The transponders each have a limited predetermined signal range, such that each transponder only receives tire pressure data from the proximately located tire pressure monitor. Further, each transponder is provided with a unique identification code that corresponds to where the tire is mounted on the vehicle.
During operation of the system, the tire pressure monitor collects tire pressure data from the vehicle tire and transmits the data to the transponder. Typically, the tire pressure monitor transmits the tire pressure data to its corresponding transponder via radio frequency. However, the tire pressure monitor may also transmit the tire pressure data via an inductive, ultrasonic, infrared or other suitable signal. In accordance with the invention, each transponder only receives tire pressure data from the closest tire pressure monitor. The transponder then adds its unique location identification code to the tire pressure data and re-transmits the data to the central system receiver. Thus, the central system receiver correlates the tire pressure data to a particular tire location. Because the transponders are secured to the vehicle, instead of to the tires, there is no need to reprogram the system to identify specific tire locations if the tires are removed or rotated. Further the use of radio frequency, inductive, ultrasonic and infrared signals eliminates the need for expensive coaxial cables.